Surface Potential Microscopy (SPoM)

Surface Potential Microscopy (SPoM)provides the capability to measure surface topography and surface potential (VDC) information simultaneously. Based on the macroscopic Kelvin method, a conductive afm tip is used to acquire topography   using TappingMode™ while the electrical information is extracted by applying AC and DC voltages to the afm tip. The total voltage acting on the tip is: V = VDC + VAC sin (Ω t). A dedicated feedback loop adjusts the DC voltage to the tip to zero the contact potential difference between the tip and surface at each pixel, making DC a measure of the surface potential. This versatile technique can be accomplished using LiftMode™ or in a dual-frequency one-pass fashion.